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The Imsides method

On this forum a while back "the Imisides method" was explained. The concentration of methoxide ion was said to be increased by the use of calcium oxide in potassium or sodium hydroxide/methanol solution. But calcium soap also occurred as an additional product. Calcium soap (ring around the tub) is an added problem in purification of useable, premium quality fuel. Mark Imisides said the reaction proceeded faster at a lower temperature. I have some calcium oxide but chemicals are hard to get here in Texas. I had hoped to use it on a more valuable project.

Re: Reduced oil temperature in reactor ?

Hi Wesley,

Originally Posted by WesleyB

Mark Imisides said the reaction proceeded faster at a lower temperature.

Are you saying that you think the esterfication reaction goes faster the lower the temperature and all the chemists who have been advising that the warmer the temperature the faster the reaction have been making a mistake?
Or are you talking about something entirely different that is not relevant to this discussion?

Experiments I performed a number of years ago also showed that the warmer the reaction the quicker it went.

Re: Reduced oil temperature in reactor ?

All i know is the extreme agitation and 60 degrees makes more (volumetricall fuel than original oil volume with obvious high conversion %, very sad problrm when your 1000 litres of oil makes more than 1000 litres of bio.

Re: Reduced oil temperature in reactor ?

Originally Posted by WesleyB

On this forum a while back "the Imisides method" was explained. The concentration of methoxide ion was said to be increased by the use of calcium oxide in potassium or sodium hydroxide/methanol solution. But calcium soap also occurred as an additional product. Calcium soap (ring around the tub) is an added problem in purification of useable, premium quality fuel. Mark Imisides said the reaction proceeded faster at a lower temperature. I have some calcium oxide but chemicals are hard to get here in Texas. I had hoped to use it on a more valuable project.

Hi Wesley< I don't remember mark imisides saying that a lower temperature was advantageous although I remember he did the process cold. Maybe this could be the subject of another Thread in order not to confuse the original question.

Re: Reduced oil temperature in reactor ?

The concentration of methoxide is increased by calcium oxide absorbing water from the methanol, methoxide, potassium or sodium hydroxide solution. Water decomposes methoxide. It shifts the equilibrium to the right (products side of the sodium hydroxide + methanol yields methoxide + water) . By removing the water more methoxide forms at the same temperature resulting in a faster reaction.

Re: Reduced oil temperature in reactor ?

Tony, It's Imisides not Insides. Anyway just to add, when I tried this method coming up to 3 years ago using Potassium Methoxide dried by using quicklime (CaO) the volume of glycerol recovered after processing was greatly reduced. Glycerol has a variable soap content depending on oil quality, methanol quality and type of catalyst used, but is in the order of 35%. With the dry methoxide there was virtually no potassium soap, so the glycerol volume was about 2/3 of normal.

Water washing was amazing, after the 1st wash the water was nearly clear. What lets this method down is the calcium soaps that are formed during the process. They are insoluble, so can't be removed by water washing. I tried the centrifuge and that also didn't work. I tried a magnesol treatment, also with a negative result. The only thing that worked was to filter the dried, slightly cloudy (due to calcium soaps) bio through oak chippings (3 times!) to get a zero soap result.

My conclusion was that it is too much of a 'faf' on to process like this every time.

Re: Reduced oil temperature in reactor ?

Hi everyone,
There have been many glowing claims made for this method. Unfortunately, as far as I can tell, No one has ever actually performed careful controlled comparison testing to to find out what, if anything the benefits actually are.

Apparently this method removes water produced when mixing Methanol with KOH/ NaOH to produce the methoxide which should result in less soap being produced. Ideally this should give similar results to using Anhydrous Sodium Methylate (ASM)

During the base transesterification reaction, soap is produced in two ways.
I- Neutraliztion of FFA. This will happen regardless of the water content of the methoxide
2- Soponification of the oils because of water being present. This is dependent on water being present in the reaction. Reducing the water content of the methoxide should decrease the soap produced from soponification.

The theoretical maximum yield by volume using new oil with a titration of 0 is around 104%
I have seen claims of a volume yields greater than 100% using the standard single stage base method.
This suggests that provided the oil is dry there is actually very little soap produced through soponification as a result of the water produced when mixing methanol and KOH to produce the methoxide

It would be interesting to see some real meaningful test performed and their results

Re: Reduced oil temperature in reactor ?

Tilly; Making and curing soap can take days or months. Reaction rate is a factor in synthesizing biodiesel (30 minutes?). I made potassium soap (exothermic) via palm kernel (solid) flakes and potassium hydroxide pellets plus a little heat. I used a thermometer as a stir rod (carefully). Heating the mix a little the exothermic reaction wen't up to 170 degrees centigrade. I did not add water to the mix. I did that years ago. A very little bit of water causes the reaction to proceed but for a long time. So a little water in our transesterification biodiesel making reaction is relatively fast, not much soap has time to saponify. But the free fatty acids present can make soap with calcium (di) hydroxide to produce the ring around the tub, soap scum, calcium soap. So the Imisides method might be advantageous with dry vegetable oil low in free fatty acids, like new oil. I read removing calcium soap is difficult (3 times through wood chips). By increasing the methoxide concentration the reaction may proceed at lower temperatures (energy economics).